The present invention relates to a chair system particularly useful for a dental office, but also useful in another type operatory, such as an ophthalmologist's office, wherein the head region of a subject is to be treated by an operator. Since the invention is especially useful for a dental office, it is described below with respect to this application.
At the present time, there are two basic working systems for the treatment of dental patients. In one system, the patient is placed in a sitting or semi-reclining position; and in a second system, the patient is placed in a fully reclining (or almost fully reclining) position. The services of a dental assistant may be used in both systems in order to increase the work efficiency.
In the first system wherein the patient assumes a sitting or a semi-reclining position, the dentist stands at the right hand side or behind the patient. In such a system, the lower jaw is mainly directly viewed by the dentist, but the upper jaw is indirectly viewed (e.g. via mirrors) for both quadrants of the mouth. One main disadvantage of this system is that the standing position of the dentist subjects the dentist to substantial stress and strain, thereby increasing fatigue as well as circulatory problems in the dentist's legs and spinal problems in the dentist's back. Another main disadvantage of this system is the poor visibility of the oral cavity.
In the second system, wherein the patient assumes a full (or almost full) reclining position, the dentist may sit on a stool located at the 9-12 o'clock position on the right hand side of the patient with the dental accessories on the left. This system better enables the use of a dental assistant to provide "four handed dentistry", which allows for better access to the oral cavity and reduces the work time for individual procedures. This system theoretically allows direct vision of all four quadrants of the patient's mouth, or a more comfortable position of the dentist for indirect vision. However, this system also has a number of disadvantages, including the following:
1. The reclining position of the patient produces an accumulation of large amounts of fluid at the back of the patient's throat, which is not only exeedingly uncomfortable for the patient, but also requires the dentist periodically to interrupt the treament in order to permit the patient to rid himself of this fluid.
2. Parallax error is magnified when restoring anterior teeth. This makes it difficult to achieve correct shape and symmetry in the maxillar and mandibular anterior region.
3. Parallelism during tooth preparation is sometimes difficult to judge because of side positioning of the patient's head; i.e. the field of vision of the dentist cannot be perpendicular to the abutment tooth without severe contortioning of the dentist's head.
4. The working position of the dentist places the dentist's upper arms, shoulder, neck and back muscles in tension, resulting in muscle fatigue, muscle ache and stress.